ISSN:
1432-2234
Keywords:
Correlation energy
;
Negative ions
;
Inversion barrier
;
Hyperfine coupling constants
;
Electron affinity
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract The ground state energies of CH 3 + , CH3, and CH 3 − are calculated both in the SCF (near Hartree-Fock) approximation and in the IEPA-PNO scheme including correlation energy. Due to a more appropriate choice of the basis, our SCF-values for CH 3 − are substantially better than previously published ones. Both CH 3 + and CH3 are planar whereas the equilibrium bond angles in CH 3 − are nearly tetrahedral. The inversion barrier of CH 3 − is ∼ 2kcal/mol. The force constants of the out-of-plane bending modes are changed by correlation in the case of CH3 from 0.03–1.8 mdyn/Å. The localized MO's that correspond to the CH-bonds are “bent” in the non-equilibrium geometries. The dependence of the different pair correlation contributions on the angle γ that describes out-of-plane deformation is analyzed. The electron affinity of CH3 is ∼0.3 eV. Finally the Pariser-Parr disproportionation reaction is analyzed in the light of the present results. Changes in correlation energy for this reaction amount to less than 1 eV.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00527465
